# CVE-2026-109496: Microsoft Office Visio heap-based buffer overflow

Source: https://junglewise.ai/threats/cve-2026-109496-heap-based-buffer-overflow-in-microsoft-office-visio-allows-an  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-109496 · Severity: high · CVSS 8.8 · Published 2026-11-10

Microsoft Office Visio is a diagramming and visualization tool used by organizations for creating flowcharts, network diagrams, and business process models. A heap-based buffer overflow vulnerability in Visio allows an attacker to execute arbitrary code on a user's computer when the user opens a specially crafted file, potentially leading to full system compromise.

Technologies: [Microsoft Office Visio](https://junglewise.ai/threats/technologies/office-visio). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-109496 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-109496 being exploited in the wild.

**How severe is CVE-2026-109496?** High severity, with a CVSS score of 8.8, published 10 November 2026.

**Which products and versions are affected?** Microsoft Office Visio.

**Is there a fix for CVE-2026-109496?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-109496 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-109496?** Check whether you run Microsoft Office Visio. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A heap-based buffer overflow exists in Microsoft Office Visio's file parsing functionality that can be triggered when processing a malicious Visio file. The vulnerability requires user interaction to open the crafted file over a network but does not require authentication. Exploitation allows arbitrary code execution in the context of the user running Visio.

## Affected products

- Microsoft Office Visio

## Timeline

- 2026-11-10: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-109496](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-109496)

## Related threats

- [Microsoft Office Visio heap buffer overflow](https://junglewise.ai/threats/cve-2026-109494-heap-based-buffer-overflow-in-microsoft-office-visio-allows-an)
- [Microsoft Office Visio heap buffer overflow](https://junglewise.ai/threats/cve-2026-102855-heap-based-buffer-overflow-in-microsoft-office-visio-allows-an)
- [Microsoft Office Visio heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-102857-heap-based-buffer-overflow-in-microsoft-office-visio-allows-an)
- [Microsoft Office Visio heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-102856-heap-based-buffer-overflow-in-microsoft-office-visio-allows-an)